1. Field of the Invention
The present invention relates to a magnetic sensor in which the connection between an electrode pad and an element section can be stabilized and the production process of the magnetic sensor can be simplified; and a method for producing such a magnetic sensor.
2. Description of the Related Art
A magnetic sensor including a magnetoresistive element is used as, for example, a geomagnetic sensor or an open/close detecting sensor. The electrical resistance of such a magnetoresistive element varies in response to the intensity of external magnetic fields.
FIGS. 12A to 14B illustrate steps of a method for producing an existing magnetic sensor. FIGS. 12A, 13A, and 14A are plan views of the magnetic sensor. FIGS. 12B, 13B, and 14B are sections taken along line XIIB-XIIB illustrated in FIG. 12A and lines corresponding to line XIIB-XIIB in the height direction and viewed in the direction of arrows illustrated in FIG. 12A.
In the step illustrated in FIGS. 12A and 12B, element sections 54 constituting magnetoresistive elements 52 and 53 are formed on an insulation layer 51 formed on a substrate 50, such that the element sections 54 have a meandering shape. For example, the element sections 54 are formed so as to have a multilayer structure constituting a giant magnetoresistive element (GMR element).
Then, in the step illustrated in FIGS. 13A and 13B, electrode layers 55 electrically connected to the two longitudinal ends of each element section 54 are formed so as to extend from the two ends of the element section 54 toward the outside. The electrode layers 55 are formed of a good conductor such as Au or Cu. The film thickness of the element sections 54 is several hundred angstroms. However, the electrode layers 55 can be formed so as to have a film thickness sufficiently larger than the film thickness of the element sections 54.
Then, an insulation layer 56 is formed on the element sections 54, the electrode layers 55, and the insulation layer 51. Contact holes 57 having a recessed shape are formed by etching or the like in the insulation layer 56 positioned on the electrode layers 55.
Then, as illustrated in FIGS. 14A and 14B, electrode pads 58 are formed in the contact holes 57 by plating Au to electrically connect the electrode pads 58 to the electrode layers 55.
As described above, the electrode layers 55 have been formed in an independent step so as to extend from the element sections 54 constituting the magnetoresistive elements 52 and 53. In this case, the element width of the element sections 54 is very small value of about several micrometers and the width between the element sections is also very small. Thus, alignment with high accuracy is required for forming the electrode layers 55 and the formation of the electrode layers 55 at a position deviated with respect to the element sections 54 tends to cause instability of the electrical connection between the electrode layers 55 and the element sections 54.
In addition, the step of forming the electrode layers 55 has been performed as a step independent from the step of forming the element sections 54, which increases the number of steps. In this case, additional material is required for forming the electrode layers 55, which increases the production costs.
Japanese Unexamined Patent Application Publication Nos. 2007-242989 and 2002-319110 are examples of related art.